The aim of this project is to characterize the properties of voltage gated channels and synaptic transmission of hippocampal inhibitory neurons in the developing brain and how these properties impact hippocampal function under both physiological and pathological conditions. Although much is known about their neurochemistry, their role in the local circuits and the basic electrophysiological properties of inhibitory interneurons, little is known about the specific ionic or ligand gated channels expressed on this highly divergent population of cells. A major part of our effort is to understand the ionic mechanisms which regulate the activity of these cells and how these mechanisms impact hippocampal function. It is hoped that these mechanisms may be potentially exploited in the future treatment of a variety of pathological conditions such as electrographic seizure activity, ischemic cell damage and stroke. Our work over the past year has focused on a particular population of inhibitory neurons, the CA1 stratum oriens/alveus interneuron. Particularly we have begun to investigate and characterize the compliment of potassium (K) channels present on these cells using both an electrophysiological and a molecular approach. In addition we have begun to characterize the role of these stratum oriens/alveus interneurons during the plastic phenomena of long term depression and potentiation. The role of stratum oriens/alveus interneurons in the high K+ -induced electrographic seizure model of epilepsy has also been studied. The characterization of the basic physiological and pharmacological properties of these cells is an essential first step for the more detailed study proposed.